Can anyone provide the information, why Cooling coils shall be placed before the heating coils in HVAC. Is there any reason behind of the this arrangement?
Where Fresh air type HVAC to be used rather than recirculation?
I am bit confusing on this aspect. Looking eagerly for a suitable information from our experts.
Thanking you
Pulla Reddy Karnati.
If cooling coils are used for dehumidification then the cooling coils need to over-cool the air so the dew point is reached and condensation happens. Heating coils then re-heat the air to desired supply temperature.
In locations with freezing winter temperatures an additional heating (pre-heat or frost) coils are placed as first to protect downstream filters, water coils and other equipment against freezing.
Adrian
[quote=Pulla Reddy]Can anyone provide the information, why Cooling coils shall be placed before the heating coils in HVAC. Is there any reason behind of the this arrangement?
Where Fresh air type HVAC to be used rather than recirculation?
I am bit confusing on this aspect. Looking eagerly for a suitable information from our experts.
Thanking you
Pulla Reddy Karnati.[/quote]
You need to do quite some reading mate. HVAC is not a something that one can learn over night. As explained by Adrian, the use of cooling and heating coils is to maintain the dew point and control condensation. Choice of fresh air v/s recirculation depends on many factors. I will recommend reading ISPE guidelines on HVAC for basic understanding of the system.
Best Regards,
Swagat
Hi Pulla,
Also check out this publication from our learning site:
http://www.learnaboutgmp.com/book/an-easy-to-understand-guide-to-hvac-validation-15
Regards
Is it possible to manufacture two different product under same AHU?
looking forward with great anticipation.
thanking you in advance
Best regards
Raj
Dear Swagat,
Can you list out some factors influence to use fresh air HVAC system rather than recirculate?
[COLOR=#800000]1)In order to maintain the room temperature and humidity in control manner, filtered air is passed through first cooling coil then followed by heating coil.
2)Once through system is used where highly active products are being manufactured. [/color]
Can different classes of area be maintained with same AHU,
for Example- Can a single AHU maintain Grade B & Grade C togather???
Any regulatory ref???
Yes. One AHU can supply different grades of Air (Grade B,C, ect). This is common for gowning into an area. The gowning rooms are typically lower Grade than the processing rooms, yet the air will come from the same AHU. The difference in the areas might be the number of HEPA filters, the location of the returns, and the air exchange rates in each area.
That being said,be aware when mixing different types of products, as cross contamination is an issue. In this case you might need two separate air handlers (in some cases two separate facilities, for example for beta-lactams like penicillin).
Also, be aware of the returns - any air going back to the AHU in re-circulation must be thought through, as there is some risk for cross contamination. At times re-circulation isn’t an option, at other times it is ideal (to save on utility costs).
If re-circulation is an issue, you can have some areas with return duct work for low/no-risk areas, and other areas which do not return (vent to atmosphere).